1. Field of Invention
The invention relates generally to computer systems. More particularly, methods and apparatus for managing a lifecycle of a resource adapter by an associated application server.
2. Description of Relevant Art
In modern Enterprise Information Systems (EIS) is formed to include a number of EIS resources. An EIS resource provides EIS-specific functionality to its clients examples of which include a record or set of records in a database system, a business object in an ERP system, and a transaction program in a transaction processing system. Generally, an EIS is formed of a number of interconnected personal computers, workstations, mainframes, and the like along with other devices such as large mass storage subsystems, network interfaces, as well as interfaces to the public telephony systems are interconnected providing an integrated environment in which information may be shared among the various users. Typically, users may be performing a variety of operations, including order receipt, manufacturing, shipping, billing, inventory control, and other operations in which sharing of data on a real time basis provides a significant advantage over, for example, maintaining separate records and attempting to reconcile them later.
The Java 2 Platform, Enterprise Edition (J2EE) provides containers for client applications, web components (based on servlets, Java Server Pages) and Enterprise JavaBeans components. These containers provide deployment and runtime support for application components as well as an integrated view of the services provided by underlying application server for the associated application components. Containers can run on existing systems such as, for example, web servers (for the web containers) application servers, TP monitors, and database systems for EJB containers enabling EISs to leverage both the advantages of their existing systems and those of J2EE. For example, EISs can write (or rewrite) new applications using J2EE capabilities and can also encapsulate parts of existing applications in Enterprise Java Beans (EJB), Message Driven Beans (MDB), Java Server Pages (JSP) or Servlets. IN addition, EIS applications access functions and data associated with applications running on Enterprise Information Systems (EIS).
The J2EE Connector architecture defines standard contracts which allows bi-directional connectivity between enterprise applications and EISs. An architecture for integration of J2EE servers with EISs is referred to as a connector architecture. There are two parts to the connector architecture: an EIS vendor-provided resource adapter and an application server that allows this resource adapter to plug in. The contracts support bi-directional communication between the application server and the resource adapter.
In the context of this discussion, a resource adapter is a system-level software driver that is used by a Java application to connect to an EIS. Some resource adapters merely function as a passive library which execute in the context of an application thread; they do not need to create threads explicitly to do their work. But more sophisticated resource adapters may need threads for their proper functioning. Such resource adapters may use threads to listen to network endpoints, process incoming data, communicate with a network peer, do its internal work, dispatch calls to application components, etc. Even though a resource adapter could create Java threads directly and use them to do its work, an application server may prevent it from creating threads for efficiency, security and manageability reasons. In such situations, a resource adapter needs a mechanism to obtain threads from an application server to do its work.
Therefore what is required is a mechanism that allows a resource adapter to submit work instances to an application server for execution thereby allowing the resource adapter to avoid creating or managing threads directly and allowing the application server more control over its runtime environment.